1. Field of the Invention
This invention relates to novel compositions of matter useful in the preparation of lubricant compositions. In particular, the invention relates to lubricants to which have been added sufficient amounts of an additive which will impart antioxidant properties thereto.
2. Discussion of the Prior Art
Lubricating oils and greases are subject to oxidative deterioration at elevated temperatures or upon prolonged exposure to the elements. The deterioration is evidenced, in many instances, by an increase in acidity and in viscosity, and, when such deterioration is severe enough, it can cause metal parts to corrode. Additionally severe oxidation leads to a loss of lubricating properties of the oil, and, in aggravated cases, to complete breakdown of the lubricated part or of the entire machine. In combatting oxidation, many additives have been tried, but many of them are only marginally effective except at high concentrations, especially when the lubricants are subjected to drastic oxidizing conditions.
The compositions of this invention are novel. U.S. Pat. No. 3,585,137 discloses, as a metal passivator in ester lubricants, an anthranilamide compound. However, anthranilamide and the other "useful compounds" set forth in columns 4 and 5 of this patent are not the same as the present compounds.